1. Technical Field
The present invention relates to a mass spectrometer. More particularly, the present invention relates to a mass spectrometer provided with a function for executing auto-tuning.
2. Background Art
In a device such as a mass spectrometer (MS), a gas chromatograph mass spectrometer (GC/MS), or a liquid chromatograph mass spectrometer (LC/MS), it is necessary to maintain the mass resolution or sensitivity at an extremely high level. This is indispensible to allow the performance of the device to be exhibited maximally and is, at the same time, necessary to maintain the reproducibility of analytical results.
Therefore, it is necessary for the voltage applied to each part such as an interface (section for ionizing a liquid sample), an ion guide, a quadrupole voltage, an ion trap, or an ion detector to be respectively kept at the correct level. However, in step with the use of the device and as time passes, deterioration occurs due to factors such as the adherence of the sample to the surface, the oxidation of the surface, or the misalignment of the physical arrangement, which leads to changes in the proper value of the applied voltage. In other words, the mass resolution or sensitivity decreases.
Accordingly, it is desirable to periodically perform tuning to adjust various parameters such as the voltages applied to electrodes to optimal values using a standard substance with known constituent types or concentrations at a frequency of approximately once per month and at least approximately once every six months, for example. Although tuning was previously performed as a manual procedure, in recent years it is common for devices to be equipped with an auto-tuning function for performing tuning automatically (for example, see Patent Literature 1).
When performing auto-tuning, a detector is ordinarily tuned first. Next, the adjustment of the sensitivity or resolution of each part is executed. In each of these adjustment modes, adjustment ordinarily begins from the inlet of the device and sequentially proceeds toward the later stages.
Tuning is performed with a method of searching for a value for which the output is maximized while varying the voltage applied to each section. In conventional auto-tuning, tuning is performed for all sections in this way from start to finish within a range designated by the user.